Role of interfacial crystallites in the crystallization of α -Fe_2O_3/ α-Al_2O_3(0001) thin films

摘要

In situ crystallization of α-Fe_2O_3/α-Al_2O_3(0001) thin films was studied in real-time synthrotron X-ray scattering experiments. We find the coexistence of α-Fe_2O_3 (hexagonal) and Fe_3O_4 (cubic) interfacial crystallites (～50-A-thick), well aligned [0.02° full-width at half-maximum (FWHM)] to the α-Al_2O_3[001] direction, in the sputter-grown amorphous films. As the annealing temperature increases up to 750 deg. C, the cubic stacking of the Fe_3O_4 crystallites gradually changes to the hexagonal α-Fe_2O_3 stacking, together with the growth of the well-aligned (WA) (0.02° FWHM) grains from the α-Fe_2O_3 crystallites.